Taurocholate transport by brush-border membrane vesicles from the developing rabbit ileum: Structure/function relationships

Journal Article · Tue May 01 04:00:00 EDT 1990 · Journal of Pediatric Gastroenterology and Nutrition; (USA)

DOI:https://doi.org/10.1097/00005176-199005000-00012· OSTI ID:6870137

Schwarz, S M; Watkins, J B; Ling, S C ^[1]

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1. New York Medical College, Valhalla (USA)

To examine the ontogenesis of bile acid transport in the rabbit ileum, brush-border membrane vesicles (12- to 20-fold purified) were prepared from 14- to 49-day-old animals. Taurocholate uptake was characterized by the emergence of secondary active, Na(+)-dependent transport at the start of weaning (21 days). Transient intravesicular accumulation (overshoot) of taurocholate occurred at 5-10 s of incubation, and the overshoot maximum increased significantly from 21 days (349.2 +/- 22.4 nmol/mg protein) to 35 days (569.0 +/- 84.3 nmol/mg protein; p less than 0.001), without further increase at maturity (49 days, not equal to 607.6 +/- 136.7 nmol/mg protein). No significant taurocholate active uptake component was noted at 14 days; however, ileal vesicles from sucklings showed carrier-mediated, Na+ D-glucose cotransport. In greater than or equal to 35-day-old rabbits, osmolarity studies at 20 s of incubation showed that only approximately 12% of (14C)taurocholate uptake was secondary to bile acid-to-membrane binding. Conversely, at 20 min, greater than 95% of radiolabel incorporation represented solute bound to the external and/or internal membrane surface. Arrhenius plots establish brush-border membrane taurocholate uptake as an intrinsic, lipid-dependent process, with a slope discontinuity between 24 and 28 degrees C, similar to the membrane lipid thermotropic transition region. Steady-state fluorescence polarization studies (1,6-diphenyl-1,3,5-hexatriene) demonstrate a temporal association between the maturation of taurocholate uptake and age-related decreases in ileal brush-border membrane fluidity. These data indicate that maturation of bile acid secondary active transport in the rabbit ileum may be regulated, at least in part, by changes in brush-border membrane lipid dynamics.

• OSTI ID: 6870137
• Journal Information: Journal of Pediatric Gastroenterology and Nutrition; (USA), Journal Name: Journal of Pediatric Gastroenterology and Nutrition; (USA) Vol. 10:4; ISSN 0277-2116; ISSN JPGND
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL COMPOUNDS
ANIMALS
BILE ACIDS
BODY
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
DIGESTIVE SYSTEM
GASTROINTESTINAL TRACT
HYDROXY COMPOUNDS
IN VITRO
INTESTINES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
MEMBRANE TRANSPORT
MEMBRANES
MUCOUS MEMBRANES
ONTOGENESIS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
RABBITS
SMALL INTESTINE
SODIUM COMPOUNDS
STEROIDS
STEROLS
TRACER TECHNIQUES
VERTEBRATES